It has become trite to say that, on September 11, 2001, Americans realized anew that it was important to pay attention to what was happening on distant shores, that developments taking place half a world away could suddenly and devastatingly threaten the lives of people here at home. This realization was important, but it cemented a view of Islamist terrorism as an external threat. The West--the United States and Europe--was the target of this terrorism, but not its source, which was to be found elsewhere, in some foreign land, where it was cooked up under the spiritual tutelage of the radical Islamist clerics of Pakistan or Saudi Arabia.

One lasting legacy of the July 7 terrorist attacks in London may be the exploding of this myth. Britons now realize that Islamist terrorism can be homegrown. What's more, the attacks have focused attention on the extent to which Great Britain has become an exporter of Islamic terrorism in recent years, by providing refuge to Islamist radicals from throughout the Middle East. British-based radicals have taken advantage of the country's tradition of free expression to encourage young Muslims to join Osama bin Laden's jihad, providing the spiritual inspiration--and, in several cases, the manpower--for attacks and attempted attacks, not only in Europe and the United States, but back in the Middle East, as well.

Three clerics residing in Britain have been particularly critical to the support of terrorism worldwide: Sheik Omar Bakri Mohammed, Abu Hamza Al Masri, and Abu Qatada. In fact, German law enforcement documents we recently obtained indicate that Abu Qatada has provided much of the spiritual inspiration for Abu Musab Al Zarqawi, the most effective Iraqi insurgent leader. A look at the history of these three militants in Britain demonstrates the folly of Britain's former tolerance of such preachers and the need for better vigilance in the future.

"He [Osama bin Laden] is showing that he can use British Muslims, who are living on your own doorstep, to harm you. He doesn't have to bring people all the way from Medina and Saudi Arabia to fly over here.... If this attack was Al Qaeda, then I think it can be considered a great success for them." That's Sheik Omar Bakri Mohammed, discussing the recent London bombings over dinner last week. Since the July 7 attacks, Bakri has been on a whirlwind tour of London's TV studios, blaming Tony Blair and his Iraq policy--as well as the British public--for provoking the attacks. As a result, the Syrian-born Bakri has become perhaps the most hated man in Britain. His face has been plastered on the front pages of many British newspapers, including The Sun, which ran its story under the headline, "send him bak." "The main issue is, you are killing Muslims in Afghanistan and Iraq," he told us. "Hands off Muslim lands.... You don't want to live in the cemetery. Come out of the cemetery. Come out of Iraq."

Bakri was granted asylum in Britain in 1986 after being expelled from Saudi Arabia for extremism. In Britain, he set up Hizb-ut-Tahir, a fundamentalist organization described by the British Home Office as "extremist." Hizb-ut-Tahir wants to take power somewhere in the Muslim world to create an Islamic state from which to spread its strict interpretation of Islam. By the mid-'90s, Hizb-ut-Tahir had been banned on Britain's campuses and thrown out of most British mosques. But, in 1996, Bakri launched an even more militant organization, Al Muhajiroun ("the Emigrants"), a nod to the Prophet Mohammed's supporters, who emigrated from Mecca to Medina in the seventh century.

We first came across an Al Muhajiroun meeting in April 2000. Tucked tightly into a community hall in Walthamstow, East London, 200 men and--unusual among such organizations--100 women were raptly listening to a conference titled "Osama bin Laden and Terrorism." "We recognize the leadership of Osama bin Laden," Bakri told the gathering. On the walls, posters announced jewish occupiers: kill them when you see them, while a self-described military adviser to the group pointed out that privately sponsored military training in the United Kingdom was not a crime.

But it was only after September 11 that Al Muhajiroun began to draw significant media attention. Shoe-bomber Richard Reid was found to have attended some of its meetings. Bakri later hit the headlines when he tried to organize a conference to celebrate the "Magnificent 19," a reference to the 19 September 11 hijackers. On April 30, 2003, two Britons of Pakistani descent attacked a nightclub in Tel Aviv, killing three. One of the attackers, Asif Mohammed Hanif--who appears to hold the distinction of being Britain's first suicide bomber--used to hang out at Bakri's offices. Omar Khan Sharif, who failed to detonate his device and was found dead in the Mediterranean Sea a few days later, also attended several Al Muhajiroun meetings. After the Tel Aviv attack, Bakri told The Daily Telegraph, "I knew Sharif very well, and he used to attend regularly at my sessions. He was my brother, and I am very proud of him and any Muslim who will do the same as him." Bakri told us that Sharif had asked about the Islamic justification for suicide bombing, but denied any role in the attack.

Bakri's name is also linked to a bomb plot broken up by British police in March 2004. Five British Pakistanis are awaiting trial for planning to use half a ton of ammonium nitrate, which they had been storing near Heathrow Airport, to hit targets in the United Kingdom. Several of the plotters, including a brilliant young cricketer, Omar Khyam, attended Bakri's meetings. Khyam's uncle told an interviewer: "Omar was a normal kid until Al Muhajiroun started preaching their hatred 'round here."

Bakri told us that, while he had known some of those involved in the ammonium nitrate plot, they had cut their ties with Al Muhajiroun, finding his group "too moderate." They did not believe, for instance, in Bakri's "Covenant of Security." This novel construct, for which Bakri attributes Koranic justification, proscribes Muslims living in Britain from waging jihad there. Bakri's Covenant of Security was never more than a wafer-thin lid on the pressure-cooker atmosphere his inflammatory preaching had created. And, in 2004, during a tirade outside the U.S. Embassy against abuses at Abu Ghraib, Bakri declared the Covenant dead. Bakri also told Publica, a Portuguese magazine, that a "very well-organized" group in London "has a great appeal for young Muslims.... I know that they are ready to launch a big operation." Alarmingly, Bakri told us that he thought there were more attacks to come. Even he expressed concern at the "jihadist tendencies" of some of his former followers who now "insult" him for not directly urging attacks on Great Britain and who "really dream, day and night, to be like Abu Musab Zarqawi."

If Bakri is a cheerleader for bin Laden's jihad, Abu Hamza has been something of a recruiter. It seems as if no self-respecting jihadist coming through London passed up the opportunity to attend the Finsbury Park Mosque, where Abu Hamza, who became a British citizen through marriage, preached. Zacarias Moussaoui, the twentieth September 11 hijacker, was a frequent visitor to the mosque, as were Richard Reid and Nizar Trabelsi, a Tunisian former professional soccer player who was instructed by bin Laden to blow up a nato base in Belgium in the fall of 2001. (Trabelsi is now serving a ten-year sentence in Belgium.) Regulars at Finsbury Park also included Abu Doha, an Algerian who once ran Al Qaeda's Khaldan training camp in Afghanistan. Abu Doha is now in British custody, implicated in a plot to blow up Los Angeles International Airport in 2000.

By January 2003, Hamza's praise of bin Laden and the September 11 attacks had become too much for the British authorities, who prevented him from continuing to preach at the Finsbury Park Mosque. But, until his eventual arrest in May 2004, Hamza continued to pour out invective every Friday on the streets outside the mosque. Hamza's arrest came as the result of an U.S. extradition request that seems to have embarrassed British authorities into pressing their own charges against the cleric, which include the solicitation of the murder of non-Muslims and the incitement of racial hatred. It turns out that Hamza could have been prosecuted years earlier; only one of the charges against him required the tougher legislation enacted after September 11 by the United Kingdom's 2001 Terrorism Act.

Hamza's trial began just one day before the July 7 attacks, and it has since emerged that Hamza had close ties with an individual suspected of playing an important role in that operation, Haroon Rashid Aswat. Aswat is originally from Dewsbury, in northern England, where three of the bombers lived, and he is suspected of visiting the bombers in the weeks before the attacks.

There is a strong U.S. connection here, too. In late November 1999, Abu Hamza sent Aswat to Oregon to scout out a piece of land that African American jihadist James Ujaama was proposing as a training camp. In an intercepted fax to Hamza, Ujaama compared the swath of land to Afghanistan and said that guns and ammunition could be stored in bunkers. If it is proved that Hamza's protege did in fact play a key role in the London attacks, British authorities will surely regret their failure to act earlier to curb Hamza's encouragement of the London jihadists.

In contrast to Bakri and Hamza--both of whom seem to revel in the publicity their calls to jihad garner--the Jordanian cleric Abu Qatada, who first arrived in London claiming asylum in 1993, is little-known to the British public. He is, however, a much more dangerous figure. Abu Qatada is the mentor and spiritual authority for many militant jihadists, including the notorious Iraqi insurgent leader Abu Musab Al Zarqawi.

We have obtained documents from German law enforcement that explain Qatada's central role in Zarqawi's network. This information came both from the interrogation of Shadi Abdallah, a Jordanian member of Zarqawi's group arrested in Germany in April 2002, as well as German wiretaps of Zarqawi's calls to his supporters. Abdallah told his interrogators that, the same month he was arrested, Zarqawi had instructed his group to start producing explosives for an attack on Jewish institutions in Germany. Abdallah also revealed Abu Qatada's role in blessing such an operation to his interrogators: "For the religious legitimation of an attack ... this was primarily the responsibility of Abu Qatada, not of Muhannad [an alias for Zarqawi].... There is a person above Muhannad in England called Abu Qatada."

Abu Qatada's central role as the spiritual guide of European jihadists was highlighted by the fact that the members of the Spanish cell who killed 191 Madrid commuters on March 11, 2004, tried to reach him three times by phone before they blew themselves up a couple of weeks after the Madrid attacks. Indeed, the Spanish judge who indicted Abu Qatada characterizes him in the indictment as "the recognized spiritual leader of numerous extremist groups."

Abu Qatada was detained by British authorities in October 2002. An earlier raid on Qatada's house turned up $296,000 in U.K. and foreign currency, which seemingly substantiates charges in the Spanish indictment that Qatada played a role in financing a number of militant groups. Despite the fact that the judge in Qatada's case concluded that he was "at the centre in the United Kingdom of terrorist activities associated with Al Qa'ida," in January 2005, the House of Lords, the highest court of appeal in Britain, forced the government to release Qatada on the grounds that holding non-British citizens without trial was discriminatory under the laws of the European Union. For the moment, Qatada is under house arrest, but, as a British judge previously ruled, "No conditions, whether involving [electronic] tagging and the use of phones, could remove the danger that this [individual] represents."

Only now does the British government seem to be getting serious about dealing with the radical clerics that it tolerated for too long. For instance, since the July 7 attacks, British officials have cut a deal with Jordan that opens the way for Abu Qatada to be expelled to his native country, provided that he does not face torture or the death penalty. And, last week, British Home Secretary Charles Clarke outlined a set of measures that would outlaw "preaching, running a Web site or writing articles which are intended to foment or provoke terrorism." This should prevent future Bakris and Abu Hamzas from inciting impressionable young Muslim men to commit terrorist acts.

In addition, the British should institute a policy of carefully vetting clerics who are planning to settle in the United Kingdom, and they might also consider adopting a plan, already in place in France, that allows only licensed clerics to preach. We know from Understanding Terror Networks, an authoritative 2004 study of 172 jihadist terrorists from around the world by former CIA officer Marc Sageman, that half of the terrorists in his sample attended the same ten religious institutions. Indeed, six of those institutions are in Europe. The importance of that finding was further underlined as it emerged at press time that several members of both the July 7 and the July 21 bombing missions worshiped at, or passed through, Hamza's Finsbury Park Mosque, including Mohammed Siddique Khan, the suspected leader of the July 7 operation. The clear inference from all this is that, at an early stage, prosecuting--or shaming into silence--preachers like Bakri, Abu Hamza, and Abu Qatada is critical to stem the spread of the militant Islamist ideology that glorifies terrorism.